Hydraulics & Pneumatics asked Ricardo Solorzano from EEM Technologies about trends in plastics manufacturing. EEM Technologies is a distributor mainly serving Latin American markets in plastics, cement, and power generation. Here are Ricardo's thoughts on servo/variable frequency drives that can be used with high-pressure piston pumps in injection molding machines.
“We tend to serve plastic manufacturers that use both injection and blow molding techniques. As far as injection is concerned, more manufacturers are switching to systems with a servo and a variable frequency drive operating a fixed piston pump. The new drives can replace variable displacement pumps to reduce energy usage by 80%. So depending on your system needs—say you need to go positive in load or negative in load—you can use a servo with a fixed pump or a servo with a variable pump. But a fixed pump is less expensive.
“The biggest difference with these servo drives is that you don’t have to run the pump during idle cycles. In the standard unit, the pump has to stay primed, usually at around 300 psi, depending on the operation, to generate just enough flow to keep it lubricated. This 300 psi is converted directly into heat. But with the new systems, the servos can restart the system pretty quickly so that the pump can run at much lower speeds during downtime and then start back up again when power is needed.
“For example, we had this one customer that was a manufacturer for plastic chairs. He didn't believe us when we told him that this new drive technique would save him in energy costs. But his reluctance changed when he saw that his system didn't need as many coolers anymore."
Ricardo Solorzano, Brendan Casey, and Bob Sheaf are available at booth S80156 in the South Hall to talk to OEMs, manufacturers, and other attendees at IFPE. They are answering questions about hydraulic system design, maintenance, and troubleshooting, and can discuss workforce training practices, industry trends, and other topics.